Spontaneous abortion and diabetes mellitus.

In 58 consecutive pregnancies in insulin-dependent diabetic women, glycosylated haemoglobin levels were abnormally high in 78% at the time of booking for antenatal care. Spontaneous abortion was the outcome in 15 pregnancies, 10 occurring before the 15th week of gestation. Glycosylated haemoglobin levels were significantly higher in those women who aborted spontaneously than in women who delivered successfully (12.8 +/- 1.8% v. 11.2 +/- 2.3%, mean +/- s.d.). These results emphasise the inadequacy of diabetic control in the first trimester and lend further support to the importance of good control at this critical time in insulin-dependent diabetes.